Hey @ BTW....if y'all are deep into your 'phile items, DIY'ing a 'puter isn't as deep a chore as one is already with your gear....more or less....
Pick your processor and match the m/b to it....select the suitable RAM chips, and stuff the slots FULL.
You want speed...there's charts online to guide that... ;)
Start 'fresh', you'll want your current lap or box for info and guides.
T-drives are ridiculous cheap lately.....but use a SSD drive for C:
There's audio cards available now that I couldn't afford or didn't exist at the time.
Find one...not just for 'now', but for Later,
What and to what to 'out' to is potentially another rung on the upgrade spiral....
Case in point:
Studios have been in digital for awhile now, with some analog diehards still in the mix.....
You Can't Beat Them...."Surrender! ...but don't give yourself away..." ;)